BACKGROUND: More than 30 percent of patients with epilepsy have inadequate control of seizures with drug therapy, but why this happens and whether it can be predicted are unknown. We studied the response to antiepileptic drugs in patients with newly diagnosed epilepsy to identify factors associated with subsequent poor control of seizures. METHODS: We prospectively studied 525 patients (age, 9 to 93 years) who were given a diagnosis, treated, and followed up at a single center between 1984 and 1997. Epilepsy was classified as idiopathic (with a presumed genetic basis), symptomatic (resulting from a structural abnormality), or cryptogenic (resulting from an unknown underlying cause). Patients were considered to be seizure-free if they had not had any seizures for at least one year. RESULTS: Among the 525 patients, 333 (63 percent) remained seizure-free during antiepileptic-drug treatment or after treatment was stopped. The prevalence of persistent seizures was higher in patients with symptomatic or cryptogenic epilepsy than in those with idiopathic epilepsy (40 percent vs. 26 percent, P=0.004) and in patients who had had more than 20 seizures before starting treatment than in those who had had fewer (51 percent vs. 29 percent, P<0.001). The seizure-free rate was similar in patients who were treated with a single established drug (67 percent) and patients who were treated with a single new drug (69 percent). Among 470 previously untreated patients, 222 (47 percent) became seizure-free during treatment with their first antiepileptic drug and 67 (14 percent) became seizure-free during treatment with a second or third drug. In 12 patients (3 percent) epilepsy was controlled by treatment with two drugs. Among patients who had no response to the first drug, the percentage who subsequently became seizure-free was smaller (11 percent) when treatment failure was due to lack of efficacy than when it was due to intolerable side effects (41 percent) or an idiosyncratic reaction (55 percent). CONCLUSIONS: Patients who have many seizures before therapy or who have an inadequate response to initial treatment with antiepileptic drugs are likely to have refractory epilepsy.

Early Identification of Refractory Epilepsy

The International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE) have come to consensus definitions for the terms epileptic seizure and epilepsy. An epileptic seizure is a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Epilepsy is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures and by the neurobiologic, cognitive, psychological, and social consequences of this condition. The definition of epilepsy requires the occurrence of at least one epileptic seizure.

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Epileptic seizures and epilepsy : Definitions proposed by the international league against epilepsy (ILAE) and the international bureau for epilepsy (IBE)

Summary This overview of population-based studies of incidence, prevalence, mortality, and case-fatality of stroke was based on studies from 1990. Incidence (first stroke in an individual's lifetime) and prevalence were computed by age, sex, and stroke type. Age-standardised incidence and prevalence with the corresponding 95% CI were plotted for each study to facilitate comparisons. The review shows that the burden of stroke is high and is likely to increase in future decades as a result of demographic and epidemiological transitions in populations. The main features of stroke epidemiology include modest geographical variation in incidence, prevalence, and case-fatality among the—predominantly white—populations studied so far, and a stabilisation or reversal in the declining secular trends in the pre-1990s rates, especially in older people. However, further research that uses the best possible methods to study the incidence, risk factors, and outcome of stroke are urgently needed in other populations of the world, especially in less developed countries where the risk of stroke is high, lifestyles are changing rapidly, and population restructuring is occurring.

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474442203002667.pdf

Stroke epidemiology: a review of population-based studies of incidence, prevalence, and case-fatality in the late 20th century.

We have identified a novel gene containing CAG repeats and mapped it to chromosome 14q32.1, the genetic locus for Machado-Joseph disease (MJD). In normal individuals the gene contains between 13 and 36 CAG repeats, whereas most of the clinically diagnosed patients and all of the affected members of a family with the clinical and pathological diagnosis of MJD show expansion of the repeat-number (from 68-79). Southern blot analyses and genomic cloning demonstrates the existence of related genes. These results raise the possibility that similar abnormalities in related genes may give rise to diseases similar to MJD.

CAG expansions in a novel gene for Machado-Joseph disease at chromosome 14q32.1

Parkinson's Disease (PD) is a common neurodegenerative disorder. We sought to synthesize studies on the prevalence of PD to obtain an overall view of how the prevalence of this disease varies by age, by sex, and by geographic location. We searched MEDLINE and EMBASE for epidemiological studies of PD from 1985 to 2010. Data were analyzed by age group, geographic location, and sex. Geographic location was stratified by the following groups: 1) Asia, 2) Africa, 3) South America, and 4) Europe/North America/Australia. Meta-regression was used to determine whether a significant difference was present between groups. Forty-seven studies were included in the analysis. Meta-analysis of the worldwide data showed a rising prevalence of PD with age (all per 100,000): 41 in 40 to 49 years; 107 in 50 to 59 years; 173 in 55 to 64 years; 428 in 60 to 69 years; 425 in 65 to 74 years; 1087 in 70 to 79 years; and 1903 in older than age 80. A significant difference was seen in prevalence by geographic location only for individuals 70 to 79 years old, with a prevalence of 1,601 in individuals from North America, Europe, and Australia, compared with 646 in individuals from Asia (P < 0.05). A significant difference in prevalence by sex was found only for individuals 50 to 59 years old, with a prevalence of 41 in females and 134 in males (P < 0.05). PD prevalence increases steadily with age. Some differences in prevalence by geographic location and sex can be detected. © 2014 International Parkinson and Movement Disorder Society

The prevalence of Parkinson's disease: A systematic review and meta‐analysis

Epidemiology can provide understanding about the incidence, prevalence, associated mortality, natural history, and potential risk factors for the epilepsies. It can also be used to assist in planning health services for people with epilepsy. Several problems exist in the interpretation of the available data, in part due to methodological problems (1-3). We address some of these issues and highlight areas in which future epidemiological research is required.

The Epidemiology of the Epilepsies: Future Directions

Uncontrolled hypertension (HT) is an established risk factor for the development of vascular diseases. Prevalence varies in different communities and no such study has been conducted in the Parsi community living in Bombay, India. The objectives of this study were to determine the prevalence, awareness, compliance to medication and control of HT in this community. We used a 1 in 4 random selection of subjects who were ≥ 20 years of age. A questionnaire was administered and the blood pressure (BP) was measured by a doctor. HT was defined as diastolic blood pressure (DBP) ≥ 90 mm Hg ± systolic pressure (SBP) ≥ 140 mm Hg. Isolated systolic hypertension (ISH) was defined as SBP ≥ 160 mm Hg with DBP < 90 mm Hg. Subsequently, we reanalysed the data using current definition of ISH as SBP ≥ 140 mm Hg with DBP < 90 mm Hg. 2879 subjects ≥ 20 years of age were randomly selected of which 2415 (84%) participated in the study. The overall prevalence of HT in the community was 36.4%, of whom 48.5% were unaware of their hypertensive status. Of those aware of having HT, 36.4% were non-compliant with their anti-hypertensive drugs and only 13.6% had optimally controlled HT. Prevalence of ISH using the present criteria was 19.5% and 73% of hypertensives ≥ 60 years had ISH. This study shows that prevalence of HT in the Parsi community is high and nearly half are unaware of their hypertensive status. ISH is the dominant form of HT in the elderly. Compliance to treatment is poor and optimal BP control is achieved in only a small minority. The study highlights the need for regular screening coupled with educational programs to detect and optimally treat HT in the community.

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Hypertension in the Parsi community of Bombay: a study on prevalence, awareness and compliance to treatment.

• A door-to-door survey was carried out to screen a community of 14010 people (Parsis living in colonies in Bombay, India) for possible neurologic diseases. High school graduates, social workers, and medical students administered a screening questionnaire that had been shown in a pilot survey to have a sensitivity of 100% for identifying those with Parkinson's disease. Neurologists used defined diagnostic criteria to evaluate individuals positive on the screening survey. There were 46 people (25 men, 21 women) who suffered from Parkinson's disease (328.3 cases per 1000 population). The age-specific prevalence ratios increased consistently with age. Ageadjusted prevalence ratios were slightly higher for men.

Prevalence of Parkinson's disease in the Parsi community of Bombay, India.

A large part of Asia, all of Africa, and most of Central and South America are located in the area between the tropics of Cancer and Capricorn, where more than a third of the world’s population live. The two most populous countries, China and India, are largely and wholly in this region, respectively. There is no doubt that epilepsy is a major problem in tropical countries, much more prevalent than in developed countries (1,2). The impact of geographic, climactic, demographic, social, and economic characteristics is adverse in terms of the frequency of epilepsy. Information is relatively limited (l), and actions have had to be based frequently on dramatic numbers such as a report that between 1983 and 1986, 60% of psychiatric outpatients and 30% of all psychiatric and neurologic cases in Malawi were related to epilepsy (H. Meinardi, personal communication, 1993), or on data indicating prevalence rates 2 to 25 times higher than the average prevalence of six per 1,000 in developed countries (3,4). The mandate of the Commission on Tropical Diseases of the International League Against Epilepsy is to advise the ILAE Executive Committee with respect to the various factors that contribute to the high frequency of epilepsy in the tropics. The focus of our attention is the study of causes, but socioeconomic and geographic influences are difficult to separate from environmental conditions that arise as their consequence. Examples are the possibilities that malaria is the commonest cause of fever in febrile convulsions; that perinatal and life-long head trauma are the commonest origins of epilepsy in children and adolescents; or that neurocysticercosis is the commonest cause of epilepsy in adults. These statements

Epilepsy in the Tropics: I. Epidemiology, Socioeconomic Risk Factors, and Etiology

A door-to-door survey was carried out to screen a community of 14,010 people (Parsis living in colonies in Bombay, India) for possible neurologic diseases. High school graduates, social workers, and medical students administered a screening questionnaire that in a pilot survey had a sensitivity of 100% for identifying persons with epilepsy. Neurologists used defined diagnostic criteria to evaluate individuals positive on the screening survey. Sixty-six persons (43 males, 23 females) suffered from epilepsy (4.7 cases/1,000). Of those, 50 (34 males, 16 females) had active epilepsy (3.6 cases/1,000). The age-specific prevalence ratios remained fairly constant for each age group except for a small peak in the group aged 20-39 years for all epilepsy cases combined. Age-adjusted prevalence ratios were higher for males. The most common seizure type was partial (36 cases). The most frequently associated conditions were cerebral palsy and mental retardation. The majority of individuals were receiving medication as of prevalence day (47 cases).

Nadir E. Bharucha

Papers

The Epidemiology of the Epilepsies: Future Directions

Hypertension in the Parsi community of Bombay: a study on prevalence, awareness and compliance to treatment.

Prevalence of Parkinson's disease in the Parsi community of Bombay, India.

Epilepsy in the Tropics: I. Epidemiology, Socioeconomic Risk Factors, and Etiology

Prevalence of epilepsy in the Parsi community of Bombay.